Concrete mixer



May 30,1944. G. MAx N, JR 2,350,285

CONCRETE MIXER Filed Aug. 17; 1942 6 Sheets-Sheet 1 MM fi/Fnwy MIXER J".

y 30, 1944- e. MAXON, JR I Q 2,350,285

CONCRETE MIXER May-30, 1944. e. MAXON. JR

' CONCRETE MIXER Filed Aug. 1'7, 1942 6 Sheets-Sheet 3 mom I May 30,1944. MAXQN, JR 2,350,285

CONCRETE MIXER Filed Aug; 17, 1942 e Sheets-Sheet 4 y 4-' I e. MAXON, JR 2,350,285

CONCRETE MIXER Filed Aug. 17, 1942- 6 Sheets-Sheet 5 May 30, 1944. G. MAXON, JR 2,350,285

CONCRETE MIXER Filed Aug. 17, 1942 6 SheetsSheet 6 film Way Maxun J27 'a mounting for the drum.

Patented May 30, 1944 CONCRETE MIXER Glenway Maxon, Jr., Milwaukee, Wis, assignor to The T. L. Smith Company, Milwaukee, Wis., a corporation of Wisconsin Application August 17, 1942, Serial No. 455,094

18 Claims.

This invention relates to concrete mixers and refers particularly to truck or transit mixers in which the drum is rotatably mounted on the chassis of a truck or other road vehicle.

Due to the unevenness of the terrain over which trucks are driven, their chassis mustbe so constructed as to permit a degree of twisting and weaving. Any interference with the freedom of a chassis to so adjust itself to irregularities places severe structural strains" on the chassis.

Consequently, it is important that a mixer mounted on the chassis of a truck or other similar road vehicle be so designed as not to resist this tendency to twist and weave. Rigid frames braced against twisting are thus impractical as Instead the drum should be so mounted that the rear end thereof may be shifted laterally as the truck chassis twists or weaves.

This has been recognized in the past as evidenced by Patent No. 1,908,811, issued to Charles F. Ball, May 16, 1933. g

One of the problems created by the twisting of the truck chassis is the difficulty of maintaining alignment between the rear endof the mixing drum and the combined charging hopper and sealing door. In truck mixers of the type with which this invention is concerned, the drum is charged and discharged through its rear open end, the charging being effected through a'ieed chute which carries a closure or sealing door provided with an annular rotatable part engaging the mouth of the drum to revolve therewith.

It is therefore essential to maintain coaxiality between the rotatable portion of the closure and 'the drum and as the rotatable portion of the closure is carried by the charging hopper, it follows that the charging hopper must be held in a definite position with relation to the open end of the drum regardless of the weaving to which the truck chassis and the mixer mounted thereon may be subjected.

To a degree this is suggested in the aforesaid patent to Ball, but merely using the same structure to support the rear end of the drum and the combined charging hopper and closure is not sufiicient. In addition, that part of the supporting structure that carries the charging hopper must be held in a fixed position with relation 'manner of rotatably supporting the rear open end of 'the drum and also carrying the combined charging hopper and closure which not only assures alignment between the mouth of the drum and the charging hopper, but also enables the retention of a fixed relationship between the mouth of the drum and the supporting structure to thereby assure a tight fit between the closure and the mouth of the drum regardless of twisting or weaving of the truck chassis.

To attain this object, it is essential that the supporting structure for the open rear end of the drum be capable of twisting onits upright or longitudinal axis so that its upper end, which carries the rollers on which the drum is supported, can retain a position normal to the drum axis regardless of the fact that any lateral displacement of the rear end of the drum as a result of twisting or weaving of the truck chassis causes the mouth of the drum to assume angles considerably different from that it occupies when the drum is in its normal position.

Stated in another way, it is an object of this invention to provide a new and improved manner of supporting the drum and the combined charging hopper and closure whereby the closed front end of the drum is supported by a selfaligning swivel bearing which allows universal swinging movement of the rear end of the drum, while its open rear end and also the combined charging hopper and closure are supp rted in an elevated position by a leg structure which is torsionally resilient so that the upper end thereof which carries the hopper and the rollers on which the drum rests is free to accommodate itself to the open end of the drum as it swings about the center of the self-aligning bearing.

Another object of this'invention is to provide an improved manner of holding the closure against the mouth of the drum.

In this connection it is another object of this invention to provide control'mechanism for the closure so constructed and designed that all force required to hold the closure shut is localized at the open end of the drum and not transmitted to the truck chassis or the bearing carrying the front end of the drum.

Another object of this invention is to provide a closure actuating mechanism which is entirely exteriorly of thejcha rging hopper or feed chute so as not to obstruct the flow of materials into the drum.

Still another object of this invention is' to support the open rear end of the drum on its supporting structure in such a manner that the supporting structure is held aligned with the drum and is secured against outward displace- :(not shown) ment axially of the drum so that the closure actuating mechanism may be mounted on the supporting structure to apply closing force on the door without imposing stress or strain upon the truck chassis or the forward drum hearing.

A further object of this invention is to provide a support for the open rear end of the drum which incorporates a simple adjustment to insure prop- The accompanying drawings illustrate one complete example of the physical embodiment of d theinvention constructed in accordance with the .best mode so far devised for the practical application'of the principles thereof, and in which:

Figure 1 is a perspective view of a truck mixer constructed in accordance with'this invention;

Figure 2 is a side elevational view thereof;

Figure 3 is an enlarged detail sectional view through the open end of the drum;

Figure 4 is an end view of the mixer I Figure 5 is a detail sectional view taken through Figure 3 on the plane of the line 5--5;

Figure 6 is a view partly in side elevation and partly in section diagrammatically illustrating the rear end of a drum and its combined feed chute and closure, but illustrating a mechanically different manner of supporting the drum to illustrate the principle involved;

Figure 7 is a detail Sectional view taken J through Figure 4 on the plane of the line I-'l;

Figure 8 is an end View of one of the adjustable drum Supporting rollers to illustrate the manner in which adjustment is effected;

Figures 9 and 10 are top plan views of the drum and its supports to illustrate the manner in which the support for the elevated open rear end of the drum accommodates itself to the drum; and Figure 11 is a rear end view of the structure shown in Figure 10.

.Referring now particularly to the accompanyfin g drawings, in which like numerals indicate likeparts, the numeral 5 designates the drum of a truckor transit concrete mixer the front end lot which is closed by a head 6 while its rear end is open to permit charging and discharging the drum. n

The drum is mounted for rotation on an inclined axis with its closed front end lowermost. A self-aligning swivel bearing 'I mounted on a pedestal 8 and having a shaft extension 9 which projects from the head of the drum journalled ,therein rotatably mountsthe lower front end of the drum in a manner permitting universal swinging movement of the open rear end of the drum. v

The raised rear end of the drum is rotatably ,carried by a supporting structure indicated generally by the numeral l0. The pedestal 8 and the supporting structure ID are both mounted either directly, on the chassis "of the truck or other road vehicle or on sills H which in turn are secured to the truck chassis Inasmuch as it forms no part of this invention, the means by which rotation is imparted to the drum has not been illustrated. It is sufficient to note that in accordance with conventional practice, the drum may be provided with a ring gear with which a drive pinion meshes.

The supporting structure [0 which is substantially yoke-like in its formation comprises a collar l2 embracing the open end of the drum and supporting legs l3 welded or otherwise secured thereto. An apron I3 connects the lower portions of the legs and their extreme lower extremities are pivoted to the sills I l as at [4.

The yoke-like supporting structure must be suificiently torsionally flexible to allow its collar I2 to retain a fixed relationship with the open end of the drum regardless of changes in angularity the plane of the open end of the drum may undergo as a result of twisting and weaving of the truck chassis.

This is graphically illustrated in the more-orless diagrammatic views of Figures 9, 10 and 11. As there shown, when the drum swings sidewise in response to twisting of the truck chassis, the

plane of its open end revolves about the center of the swivel bearing 1 as would the plane of the segment of a sphere concentric to the bearing 1. To maintain proper alignment between the open end of the drum and the combined charging hopper and closure, the collar l2, which carries the combined charging hopper and closure, follows the changing angularity of the open end of the drum. The manner in which the collar I2 and the open end of the drum are held against relative displacement to insure maintenance of this fixed relationship will be hereinafter fully described.

Thecollar l2 is preferably made of relatively heavy sheet metal and is roughly a truncated cone of a size to leave a space between it and the conical wall of the drum adequate to accommodate an annular flange l5 fixed to the open end or mouth of the drum.

The flange [-5 provides the customary drip ring for the drum but is of special construction to provide a conical roller track Hi. This conical roller track tapers in toward the closed end of the drum and is bounded by inner and outer annular flanges l1 and I8, respectively.

A plurality of rollers I9 carried b the collar 12 engage the track I6 to rotatably support and guide the open end of the drum. There are four such rollers, a lower load carrying pair, and an upper guiding pair. All of the rollers are of the same construction, best illustrated in Figure 3.

Like the track It, the rollers are conical but are preferably crowned so as to accommodate any slight inaccuracies in the angular relation- .ship between the axes of the conical track and the conical rollers.

The actual support for the rollers consists of spaced inner and outer hub members 20 and 2| each welded to the collar i2 and extending through an opening therein. Respectively small and large diameter bores in the hub members 20 and 2| have small and large diameter end portions 22 and 23 of roller shafts received therein.

The rollers are journalled on central portions 24 of the roller shafts, and inasmuch as these central or intermediate portions of the shafts are eccentric to the shaft portions 22 and 23, rotationv of the shafts adjusts their rollers toward and from the axis of the drum.

To facilitate such adjustment and to hold the shafts in adjusted positions, flanges 25 are formed on their large diameter ends 23 to overlie the hub portions 2|. A plurality of bolt holes 26 in each flange 25 and a lesser number of tapped holes in the hub portion 2| provide for the reception of cap screws 21 by which the shafts are secured in different positions of rotary adjustment.

Covers 28 of sheet metal are fitted over the exposed portions of the rollers to provide a neat external appearance and protect the rollers.

As hereinbefore stated, the rear elevated end of the drum is open to permit charging and discharging of the drum. Charging of the drum is facilitated by the provision of a charging hopper or feed chute 30 and discharging of the drum contents which occurs upon reversal of its direction of rotation, is effected through a suitable discharge chute (not shown) provided with a funnel-like receiving hopper mounted under-the edge of the mouth of the drum. The discharge chute and its associated mechanism, however, forms no part of this invention and therefore has not been shown.

The charging hopper or feed chute is part of a combined charging hopper and sealing door or closure by which the open end of the drum is closed. In its essentials the combined charging hopper and sealing door is like that illustrated in the patent to H. C. Peters et al., No. 2,267,801, issued December 30, 1941.

Accordingly, the feed chute 30 has a stationary fiat disc-like plate 3| encircling its lower end and fixed thereto, the periphery of which has a rotatable flat ring 32 mounted thereon. The latter, in the closed position, bears against the mouth of the drum which is preferably provided with a wear resisting gasket 33 set into an annular groove in the end face of the drip ring I5.

Thus, in the closed position, the rotatable part 32 of the closure revolves with the drum and obviously if excessive wear and binding due to shifting of the rotatable part 32 of the closure on the gasket 33 is to be avoided, coaxiality must be maintained between the drum and the closure. Also, if a tight seal is to be maintained between the closure ring 32 and the gasket 33 all around the mouth of the drum, the combined charging hopper and closure must retain its proper relationship with the mouth of the drum.

To this end, the combined charging hopper and closure is mounted from the collar I2 which, as noted hereinbefore, carries the rollers I9 on which the open end of the drum rests. While the specific manner in which the collar I2 supports the combined charging hopper and sealing door may be modified to suit design, in its essential elements it comprises spaced hinge plates 34 welded or otherwise fixed to the collar and having an extension 35 on the charging hopper re- .ceived therebetween and pivoted thereto.

The location of the hinge 36 between the plates 34 and the hopper extension 35 is such that when the combined charging hopper and sealing door is swung down to its closed position the rotatable part 32 of the door lies flat against the mouth of the drum.

1 .Opening and closing movement is imparted to the combined charging hopper and sealing .door in such a manner that the force required to press the door closed imposes no strain upon the truck chassis or upon the self-aligning bearing 1 at the front end of the drum.

One manner of so actuating the combined charging hopper and sealing door consists in the provision of a pair of arms 3'! pivoted as at -38 to the opposite sides of the hopper and con- III) nected at their lower ends to actuators 39 and 40,

the former being a gear segment and the latter a lever. Both actuators are fixed to a cross shaft 42 journalled in suitable bearings 43 carried by the supporting legs I3.

The relationship of these parts is such that upon oscillation of the shaft 42 in one direction the combined charging hopper and sealing door raises to an open position, while oscillation in the opposite direction closes the same. I

In the closed position, the connections of the arms 31 with their respective actuators cross dead center to hold the door closed and pressed against the mouth of the drum.

Oscillation is imparted to the cross shaft 42 by means of a pinion 44 driven by a hand wheel 45 and meshing'with the gearsegment 39.

By virtue of the conical formation of the roller track I5 the support for the open end of the drum, in analogy,constitutes a combined radial and thrust bearing as indicated at 46 in Figure 6. Hence, outward axial displacement of the yoke structure comprising the collar I2 and the supporting legs I3 to disengage the same from the open end of the drum is prevented. The tension applied to the arms 3! to press the closure against the mouth of the drum thus involves only localized strain. No strain is imparted to the truck chassis or the self-aligning bearing at the closed front end of the drum.

The manner in-which this is accomplished is readily apparent from Figure 6, which, as stated, draws an analogy between the specific structure employed and a simple combination radial and thrust bearing. In the construction shown in Figure 6, the charging hopper and sealing door is shown to be opened and closed by an air cylinder 41 or the like which may, of course, be used instead of the manually driven pinion and gear.

As noted above, outward axial displacement of the yoke-like supporting structure is prevented by the conica1 formation of the roller track. Thus, as long as the combined charging hopper and sealing door is closed the rollers will all tightly engage the track due to the closing pressure applying an outward force on the collar I2, and the closure will be flat against the mouth of the drum regardless of changes in angularity of the open end of the drum that take place as the rear end of the drum moves in response to twisting or weaving of the chassis.

The same retention of fixed relationship between the drum and the collar I2 also follows as a result of the reaction of the weight of the drum on the rollers tending to force the upright yokelike supporting structure rearwardly to keep the rollers tight against the track when the closure is open as well as when it is closed.

This follows from the fact that the hinge pins I4 which connect the yoke structure to the chassis are so positioned with relation to the points of load application (the lower supporting rollers) that the nearly vertical line of reaction falls to the rear of the hinge I4 (to the right in Figure 2) and thus tends to swing the upper end of the yoke structure rearwardly.

Any suitable seal may be employed between the rotatable and nonrotatable parts of the closure. In the construction shown, the inner peripheral edge portion of the rotating part 32 overlies a flat flange 50 fixed to the inner face of the stationary ring 3 I, and secured to the outer face of the stationary part 3I and extending out over the rotatable part 32 is an annular angle member 5|. A plurality of clips 52 Welded to the channel and bolted to the stationary part 3| hold the annular angle and the flange 50 in place.

A fiat ring 53 carried by the rotating part 32 rides in the angle 5| and provides the bearing per se between the nonrotating and the rotating parts of the closure. A plurality of spacers 54 mount the flat ring on the rotating member 32.

Grease or other suitable lubricant is supplied to the bearing between the flat ring 53 and the angle and the clearance between the rotating part 32 and the stationary flange 50.

From the foregoing description, taken in connection with the accompanying drawings, it will be readily apparent that this invention provides a substantial improvement in truck mixers in that it not only accommodates weaving and twisting of the truck chassis without imposing strain upon the mixer and without causing misalignment between the drum and its closure, but further in that it provides an effective manner of holding the closure against the mouth of the drum Without exerting pressure on the front bearing and without imposing any strain on the truck chassis.

. It will also be readily apparent to those skilled in the art, that this invention enables the appearance of the mixer to be materially improved through the use of the conical collar which embraces the open end portion of the drum and covers its drip ring and roller track.

What I claim as my invention is:

1. In a concrete mixer: a rotatable mixing drum having an outer open end and an inner closed end; an annular shoulder on the drum facing inwardly toward the closed end; a yoke bearing axially against the shoulder and held thereby against outward axial movement with respect to the drum; a movable closure for the open end of the drum movably carried by the yoke; and means carried by the yoke for actuating the closure to and from open position and for pressing the closure against the open end of the drum.

2. In a concrete mixer: a rotatable mixing drum having an open end; an annular shoulder on the drum facing toward the opposite end of the drum and away from said open end; a yoke bearing axially against the shoulder and held thereby againstoutward axial movement with respect to the drum; a movable closure for the open end of the drum; means movably supporting the closure from the yoke; and means carried by the yoke and connected with the closure for pressing the same against the open end of the drum.

3. In a concrete mixer: a rotatable mixing drum having an open end; an annular flange on the drum contiguous to its open end; a movable closure for the open end of the drum; and means forming a free running thrust bearing engaging the annular flange to be supported thereby against axial movement away from the open end of the drum; and means connected between said free running thrust bearing and the closure for pressing the closure against the open end of the drum.

4. In a concrete mixer: a rotatable mixing drum having one end open and the other end closed; means rotatably mounting the drum including a bearing at its'closed end;- an annular Cir supporting means whereby the closure is mounted for movement to and from a closed position engaging against the open end of the drum; and means supported by said shoulder and connected with the closure for pressing the closure against the open end of the drum so that the closing force is applied to the closure without imparting thrust on the bearing at the closed end of the drum.

5. In a concrete mixer: a rotatable mixing drum having an open end with a drip ring around the edge thereof, said drip ring providing an annular shoulder facing toward the opposite end of the drum; a yoke, structure having a part thereof embracing the open end portion of the drum; rollers on the yoke structure engaging the annular shoulder and holding the yoke structure against axial movement away from the drum; a closure for the open end of the drum; means mounting the closure from the yoke structure for movement to and from a closed position engaging against the open end of the drum; and means carried by the yoke structure and connected with the closure for pressing the closure against the open end of the drum.

6. In a concrete mixer: a rotatable mixing drum having one end open and its other end closed; a bearing rotatably supporting the closed end of the drum; an annular roller track encircling the open end portion of the drum; the peripheral surface of said track being conical and tapering in toward the closed end of the drum; a yoke structure for supporting the open end of the drum; a plurality of rollers on said yoke structure engaging the conical peripheral surface of the roller track whereby the open end of the drum is rotatably supported and the yoke structure is held against axial movement away from the drum; a closure for the open end of the drum; and means carried by the yoke structure for pressing the closure against the open end of the drum,

'7. In a concrete mixer: a rotatable mixing drum having an open end; a closure for the open end of the drum; mechanism for actuating the closure and for exerting closing pressure thereon; and common means for rotatably supporting the open end of the drum and said closure actuating mechanism, said means including an annular shoulder on the drum facing toward the opposite end of the drum and a part on said common means engaging behind the shoulder to carry the reaction forces of the closing pressure exerted on the closure.

8. In a concrete mixer: a rotatable mixing drum having an open end; a closure for the drum having a rotatable part engageable with the edge thereof so that coaxiality is required between the drum and closure; a support for the open end of the drum; means for establishing and maintaining coaxiality between the support and the drum; means mounting the closure from the support so that coaxiality is maintained between the drum and the closure in its closed position; mechanism for opening and closing the closure; and means exteriorly of the drum and axially restrained .by the drum from movement axially away from the drum for mounting the opening and closing mechanism.

9. In a concrete mixer: a rotatable mixing drum having an open end; a ring fixed to and encircling the drum, the outer surface of which provides the inner race of a combination thrust and radial bearing; a yoke structure embracing the drum near the ring and providing a roller cage; rollers on the yoke structure engaging the outer surfaces of the ring to rotatably support the drum on the yoke structure and hold the yoke structure against axial movement away from the drum; a closure for the open end of the drum; means movably mounting the closure from the yoke structure; and means on the yoke structure for pressing the closure against the open end of the drum.

10. In a concrete mixer; a rotatable mixing drum having one end open and its other end closed; a drip ring on the open end of the drum provided with a conical roller track which tapers in toward the closed end of the drum; a collar formed of rigid sheet metal encircling the open end portion of the drum and covering said conical roller track; rollers carried by said collar and engaging said conical roller track; legs supporting the collar so that the open end of the drum is rotatably carried by the collar and the collar is held coaxial with the drum and against outward displacement with respect to the drum, said collar and its supporting legs forming a yoke structure; a combined charging hopper and sealing door for the open end of the drum; means movably mounting the combined charging hopper and sealing door from the collar; and means carried by the yoke structure and connected with the combined charging hopper and sealing door for moving the same to and from closed position and for pressing the sealing door against the open end of the drum;

11. In a concrete mixer: a rotatable mixing drum having an open end; an annular roller track fixed to and encircling the open end portion of the drum; a supporting structure for the open end of the drum; rollers carried by said supporting structure and engaging the roller track to rotatably support the drum on said structure and hold said structure centered with the drum; the surface of the track traversed by the rollers being at an angle to the axis of the drum and facing the opposite end of the drum so that the supporting structure is restrained by the drum against movement axially outwardly away from the drum; a movable closure for the open end of the drum; and means carried by the supporting structure for pressing the closure against the open end of the drum.

12. In a truck mixer: a rotatable mixing drum having one end open and its other end closed; a self-aligning bearing supported on the chassis of the truck and rotatably carrying the closed end of the drum; an upright supporting structure carrying the open end of the drum; antifriction rollers on said upright supporting structure; a roller track fixed to and encircling the drum and riding on said rollers, said track being largest in diameter at its outer side nearest the open end of the drum so that the upright supporting structure is held against axial displacement outwardly of the drum; means hingedly supporting said upright supporting structure from the chassis for movement about an axis transverse to the chassis and forwardly of the line of reaction of the weight of the drum on said rollers so that the supporting structure tends to tip rearwardly; a combined charging hopper and closure for the open end of the drum; means movably mounting the combined charging hopper and closure on said upright supporting structure; and mechanism for actuating the combined charging hopper and closure and for pressing the same against the open end of the drum, said mechanism being connected with the combined charging hopper and closure and being mounted on the upright supporting structure.

13. In a truck type concrete mixer wherein a rotatable mixing drum is mounted on the chassis of a truck: a self-aligning bearing supported on the chassis and rotatably mounting one end of the drum; a roller track on the other end of the drum; a collar embracing said other end of the drum and covering the track; rollers carried by the collar and projecting from the inside of the collar to engage the track and cooperate with the self-aligning bearing'in rotatably mounting the drum; a closure -for the open end of the drum; mounting means for the closure carried:

by the collar; supporting legs fixed to the collar and supported on the chassis of the truck; and mechanism for actuating the closure mounted on said supporting legs.

14. In a truck type concrete mixer wherein the mixer is mounted on the chassis of a road .ve-: hicle: a rotatable mixing'drum open at one'end and closed at the other; a self-aligning bearing mounted on the chassis and rotatably supporting the closed end of the drum; a roller track fixed to and encircling the open end portion of the drum, said track having a conical surface which tapers in toward the closed end of the drum; a yoke structure embracing the open end portion of the drum; rollers carried by the yoke struc-' ture and engaging the conical surface of the roller track; means supporting the yoke structure on the chassis, said means allowing the 'yoke struc ture to tilt about an axistransverse to the chassis and said yoke structure being torsionally sufliciently flexible to enable that part of the yoke structure that embraces the open end of the drum to accommodate itself to the open end of the drum during weaving and twisting of the chassis; a combined charging hopper and sealing door for the open end of the drum including a part coaxial with the drum and revoluble therewith when the door is closed; and means mounting the combined charging hopper and sealing door from the yoke structure so as to insure the maintenance of coaxiality and a tight seal between the drum and the door regardless of possible twisting and weaving of the chassis.

15. In a truck type concrete mixer wherein the mixer is mounted on the chassis of a road vehicle which is subject to twisting and weaving: a rotatable mixing drum; a self-aligning bearing rotatably supporting one end of the drum above the chassis; means for rotatably supporting the other end of the drum above the chassis in a manner which causes the drum to swing radially about the center of the self-aligning hearing as the chassis twists and weaves, said means comprising an upright torsionally resilient structure; and a combination thrust and radial bearing connection between said supporting structure and the drum resisting relative displacement therebetween so that by virtue of the torsional resiliency of the supporting structure that portion thereof adjacent to said bearing connection accommodates itself to the drum notwithstanding radial swinging of the drum during twisting and weaving of the chassis.

16. In a concrete mixer of the type mounted ing up from the chassis and rotatably carrying the other end of the drum; a connection between said supporting structure and the drum resisting relative displacement therebetween, the torsional resiliency of the supporting structure allowing that portion thereof adjacent to the drum to be held against relative displacement with respect to the drum although the drum is caused to swing radially about the self-aligning bearing by twisting and weaving of the supporting chassis; and a combined charging hopper and closure carried by the supporting structure and movable to and from a position closing the adjacent end of the 17. In a truck type concrete mixer wherein the mixer :is mounted on the chassis of a road vehicle which is subject to twisting and weaving: a rotatable mixing drum open at one end and closed at theother; a self-aligning swivel bearing rotatably supporting the closedend of the drum above the chassis; an upright supporting structure hingedly connected with the chassis for movement about an axis transverse to the chassis; and cooperating means on the open end of the drum and the upper end of the supporting structure forming a combination thrust and radial bearing for rotatably supporting the open end of the drum in a manner resisting relative displacement between the drum and said supporting structure, with the open end of the drum at a higher elevation than its closed end, said supporting structure being sufiiciently flexible torsionally on its upright axis to enable the upper end portion of said supporting structure to be held against relative displacement with respect to the drum although the raised open end-of the drum is swung asubstantial distance from its normal position by the twisting and weaving of the chassis.

18. In a truck type concrete mixer wherein the mixer is mounted on the chassis of a road vehicle: a rotatable mixing drum; a self-aligning swivel bearing rotatably supporting one end of the drum above the chassis; an upright supporting structure for the other end of the drum; means hingedly connecting said supporting structure with the chassis so that the upper end of the supporting structure is movable toward and from the self-aligning bearing while being held against lateral swinging with respect to the chassis whereby that twisting and weaving of the chassis causes the upper end of said supporting structure to move laterally; and means freely rotatably supporting the drum on said upright supporting structure, said last named means comprising rollers on the supporting structure and a track on the drum riding on said rollers, said rollers and track cooperating to resist rela tive displacement between the drum and said supporting structure, and said supporting structure being sufficiently flexible torsionally about its vertical axis to enable the supporting structure to accommodate itself to th drum during lateral swinging of the drum in response to twisting and weaving of the chassis.

GLENWAY MAXON, JR. 

